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World Allergy Organization
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Disease Summaries

Ocular Allergy

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Posted: July 2004


Professor Connie Katelaris, MD, PhD
Clinical Associate Professor, Dept. of Clinical Immunology and Allergy
Westmead Medical Centre
Westmead, Australia



Definitions

Classification
Causes
Diagnosis
Epidemiology
Prevention
Treatment

Ocular Allergy: Global Overview

Definition

Allergic conjunctivitis is a broad group of allergic conditions involving inflammation of the conjunctiva. The commoner conditions are mild and do not affect the cornea. The rarer diseases involve the cornea and can be sight-threatening.

Classification

Seasonal, intermittent, IgE-mediated allergic conjunctivitis (SAC)

(click for photograph)

Perennial, persistent, IgE-mediated allergic conjunctivitis (PAC)

(click for photograph)

These common IgE mediated diseases are related to seasonal or perennial allergens. They are characterized by symptoms of ocular itching, watering and redness, and signs of hyperaemia and oedema of the tarsal conjunctival surfaces. There is frequently an association with allergic rhinitis. SAC is intermittent in nature, and, in temperate regions, follows exposure to pollen allergens in sensitized individuals. PAC is a mild, persistent form of allergic conjunctivitis resulting from continuing exposure to persistent allergens such as house dust mites.

Vernal keratoconjunctivitis (VKC)

This is a severe inflammatory disease which may be intermittent or, less frequently, persistent. VKC is, in about 60% of cases, associated with IgE-dependent hypersensitivity. The symptoms are ocular watering, stickiness, itching, and difficulty with opening the eyes on awaking. If the cornea is involved, pain, blurred vision and photophobia are experienced. The signs are giant papillary hyperplasia of the upper tarsal conjunctival surfaces, erosion of the corneal epithelium and inflammation at the limbus (click for photograph).

Atopic keratoconjunctivitis (AKC)

This is a severe disease which is associated with atopic eczema. The condition is lifelong, starting in the third of fourth decade. IgE-mediated mechanisms may be implicated. The symptoms are perpetual ocular itching, soreness, impaired vision and a sensation of dryness (click for photograph). Signs include chronic lid margin infection, chronic cicatrising conjunctivitis, eczema of the eyelids, tear abnormality, and progressive scarring and vascularization of the cornea.

Giant papillary conjunctivitis (GPC)

This disease, also known as foreign body associated papillary conjunctivitis, results from trauma caused by contact lens edges, ocular protheses or post-operative sutures. It may also evolve from spontaneous lid eversion resulting in conjunctival rubbing against the pillow, the so-called floppy eyelid syndrome. Upper subtarsal papillae, not always giant in size (> 1mm), is the hallmark sign of the disease. There is no evidence that generally IgE-sensitized individuals are at greater risk of developing the disease. The cornea is rarely involved. (Click for photograph.)

Causes 

Seasonal, intermittent, IgE-mediated allergic conjunctivitis

Seasonal, intermittent, allergic conjunctivitis is triggered by the same allergens responsible for intermittent allergic rhinitis. In the Northern Hemisphere these are tree pollens in April/May, grass pollens in June/July, and mold spores and weed pollens in July/August.

Perennial, persistent, IgE-mediated allergic conjunctivitis

Perennial, persistent, allergic conjunctivitis is triggered by house dust mites, molds and animal allergens, which may be present year round, although the symptoms do show some seasonal variation. In the Southern Hemisphere the pollen season can be all year round, depending on the region.

Vernal keratoconjunctivitis

The majority of cases of VKC are intermittent and can occur during the high pollen season, although persistent cases do occur in warm subtropical or desert climates. Published reports of the association with IgE-mediated atopic disease vary between 15% to 60%. While there is a relationship between the condition and positive skin tests, the relationship is not necessarily causal.

Atopic keratoconjunctivitis

AKC is a perennial disease which, when associated with the IgE-mediated subgroup of atopic eczema, may be exacerbated by contact with specific allergens such as house dust mites, mold spores, animal danders and rarely foods.

Giant papillary conjunctivitis 

Giant Papillary Conjunctivitis occurs in the presence of foreign bodies in the eye, such as contact lenses or ocular prostheses. Papillae develop on the upper tarsal conjunctiva along the line of contact with the source of mechanical trauma, e.g., the lens edge. The upper eyelid may be traumatized with each blink of the eye, which occurs between 10,000 and 12,000 times daily, and the area of trauma may serve as an entrance for antigen possibly derived from altered proteins or chemicals in contact lens solutions, although no single causative allergen has been identified in this condition to date.

Diagnosis of Allergic Conjunctivitis

Clinical examination and investigations

  • Appearance of the everted (flipped) eyelid. This may be performed by using a long thin object, such as a cotton bud, as a fulcrum at the top of the tarsal plate, while the eyelashes are pulled forward and up.
  • Conjunctival scrapings for eosinophils may be helpful
  • Skin prick/puncture tests or specific IgE tests to identify causative allergens

Clinical history

  • Typical symptoms
  • 80% of patients are under 30 years of age
  • Strong personal or family history of IgE-mediated diseases
  • Recurrent intermittent or persistent symptoms

Mediators of IgE-related reactions in allergic conjunctivitis

  • Histamine: Itching, redness, oedema
  • Prostaglandins: Sensitized nerves, enhanced pain, oedema and redness
  • Leukotrienes: Chemotaxis, oedema and vascular permeability
  • Chemotactic factors: Recruitment of eosinophils and neutrophils leading to tissue destruction

Differential diagnoses of allergic conjunctivitis include

  • Atopic blepharitis
  • Bacterial conjunctivitis
  • Chlamydial conjunctivitis
  • Corneal abrasion or ulceration
  • Dry eye
  • Episcleritis
  • Epithelial microcysts and vacuoles
  • Staphylococcal marginal keratitis
  • Superficial punctate keratitis
  • Tight lens syndrome
  • Viral conjunctivitis or keratitis

Ocular itching is a cardinal symptom of allergic eye disease and in the absence of itching an alternative diagnosis should be suspected.

Epidemiology

SAC

SAC may occur alone or as a component of seasonal/intermittent allergic rhinitis (hay fever). Both SAC and PAC are primarily diseases of young adults, and there is a slightly higher prevalence in males.

VKC

VKC is a disease of childhood and early adolescence. Genetic factors and atopic status may be involved in the development of the disease, although many patients have no familial or personal history of atopy, and may have negative allergy diagnostic tests. Thus, like atopic eczema it might represent a syndrome with allergic and non-allergic subgroups. Males are more frequently affected than females, with a ratio of 3:1. The disease usually begins before the age of 10 years and remits at the time of puberty, although the age of affected individuals ranges from 3 to 25 years of age. VKC may progress to atopic keratoconjunctivitis.

VKC occurs more frequently in warm climates and subtropical areas, in particular the Mediterranean area, central Africa, India and South America. It is also reported in Australia, China, Japan and North America. The incidence of the disease in cooler climates in Northern Europe is thought to reflect migration of susceptible individuals, and it is thought that both genetic and environmental factors contribute to the development of the disease.

AKC

AKC first occurs in the late teens or early twenties with a peak incidence between the ages of 30 – 50 years. It is more frequent in men and occurs in up to 25% of patients with atopic eczema. There is usually a personal or family history of atopic disease.

GPC 

GPC associated with contact lens use reflects the age of contact lens wearers and thus rarely occurs in children or the elderly. However when associated with post-surgical mechanical trauma, such as exposed sutures, it is more prevalent in older age groups. There is no gender predominance.

Prevention

Allergen avoidance can lead to significant improvement in symptoms of SAC and PAC. In GPC, the use of disposable contact lenses may be helpful if lens deposits are causing symptoms, and changing to daily use of disposable lenses can eliminate the condition entirely.

Treatment 

Recommendations for the treatment of seasonal, intermittent, and perennial, persistent allergic conjunctivitis are available on the GLORIA area of this website. Treatment of the rarer, more severe forms of allergic conjunctivitis requires the use of topical corticosteroids and should be managed by an ophthalmologist. Prolonged use of topical steroids in the eye can lead to secondary bacterial infection, intra-ocular hypertension, glaucoma and cataract, and thus regular monitoring is essential. To print out WAO's pocket chart on treatment of allergic rhinitis and allergic conjunctivitis, click here.

VKC

Cromones and other mast cell stabilisers may be prescribed alone, or in addition to topical steroid therapy. Mucolytic drops (acetylcisteine 5% or 10%) may be used to control the symptoms caused by abnormal mucus.

AKC

In addition to topical corticosteroid therapy, treatment of the infected lid margins with topical or systemic antibiotic may help to reduce symptoms. Cromones and other mast cell stabilizers may be of value. Treatment of eye lid eczema with steroid ointments may be of value.

GPC

The condition, fit and cleaning schedule of contact lenses or prosthesis should be reviewed. Opticrom or similar drugs may be used if required. Topical steroids should not be used for contact lens wearers, but may be given for prosthesis wearers, where no risk to damage of the eye can occur.